Person:
Brand, Oliver

Associated Organization(s)
ORCID
ArchiveSpace Name Record

Publication Search Results

Now showing 1 - 10 of 12
  • Item
    Characteristics of laterally vibrating resonant microcantilevers in viscous liquid media
    (Georgia Institute of Technology, 2012-01) Cox, Russell ; Josse, Fabien ; Heinrich, Stephen M. ; Brand, Oliver ; Dufour, Isabelle
    The characteristics of microcantilevers vibrating laterally in viscous liquid media are investigated and compared to those of similar microcantilevers vibrating in the out-of-plane direction. The hydrodynamic loading on the vibrating beam is first determined using a numerical model. A semi-analytical expression for the hydrodynamic forces in terms of the Reynolds number and the aspect ratio (beam thickness over beam width) is obtained by introducing a correction factor to Stokes’ solution for a vibrating plate of infinite area to account for the effects of the thickness. The results enable the effects of fluid damping and effective fluid mass on the resonant frequency and the quality factor (Q) to be investigated as a function of both the beam’s geometry and liquid medium’s properties and compared to experimentally determined values given in the literature. The resonant frequency and Q are found to be higher for laterally vibrating microcantilevers compared to those of similar geometry experiencing transverse (out-of-plane) vibration. Compared to transversely vibrating beams, the resonant frequency of laterally vibrating beams is shown to decrease at a slower rate (with respect to changes in viscosity) in media having higher viscosities than water. The theoretical results are compared to experimental data obtained for cantilevers completely immersed in solutions of varying aqueous percent glycerol. The increases in resonant frequency and Q are expected to yield much lower limits of detection in liquid-phase chemical sensing applications.
  • Item
    Workshop micro-and nanosystems (MNS) horizon 2040
    (Georgia Institute of Technology, 2010-09-30) Brand, Oliver
  • Item
    SGER: resonant microsensor based on decoupled sensing scheme for liquid-phase biochemical sensing
    (Georgia Institute of Technology, 2010-08-01) Brand, Oliver ; Beardslee, L. A.
  • Item
    Effect of Stress Due to Plastic Package Moisture Absorption in Hall Sensors
    (Georgia Institute of Technology, 2009-06) Cesaretti, Juan Manuel ; Taylor, W. P. ; Monreal, G. ; Brand, Oliver
    Commercial magnetic sensors based on the Hall effect are usually encapsulated in non-hermetic plastic packages. These plastic packages are known to swell in high humidity conditions due to moisture absorption. This swelling will modify the stress seen by the Hall sensor, causing the Hall sensitivity to be altered due to the piezo-Hall effect. The sensitivity drift, which is random in nature, may become the long-term stability limiting factor in high-end sensors. The objective of this work is to characterize in depth the sensitivity change due to moisture absorption and to review and implement two Hall sensitivity compensation methods.
  • Item
    Cancellation of environmental effects in resonant mass sensors based on resonance mode and effective mass
    (Georgia Institute of Technology, 2009-06) Naeli, Kianoush ; Brand, Oliver
    novel technique is developed to cancel the effect of environmental parameters, e.g., temperature and humidity, in resonant mass sensing. Utilizing a single resonator, the environmental cancellation is achieved by monitoring a pair of resonant overtones and the effective sensed mass in those overtones. As an eminent advantage, especially compared to dual-mode temperature compensation techniques, the presented technique eliminates any need for previously measured look-up tables or fitting the measurement data. We show that a resonant cantilever beam is an appropriate platform for applying this technique, and derive an analytical expression to relate the actual and effective sensed masses on a cantilever beam. Thereby, it is shown that in applying the presented technique successfully, the effective sensed masses must not be the same in the investigated pair of resonance overtones. To prove the feasibility of the proposed technique, flexural resonance frequencies of a silicon cantilever are measured before and after loading with a strip of photoresist. Applying the presented technique shows significant reductions in influence of environmental parameters, with the temperature and humidity coefficients of frequency being improved from −19.5 to 0.2 ppm °C⁻¹ and from 0.7 to −0.03 ppm %RH⁻¹, respectively.
  • Item
    Chemical microsystem based on vertical integration of sensor array and CMOS circuit
    (Georgia Institute of Technology, 2009-04-30) Brand, Oliver ; Mizaikoff, Boris
  • Item
    Dimensional considerations in achieving large quality factors for resonant silicon cantilevers in air
    (Georgia Institute of Technology, 2009-01) Naeli, Kianoush ; Brand, Oliver
    This work aims to provide guidelines for designing rectangular silicon cantilever beams to achieve maximum quality factors for the fundamental flexural resonance at atmospheric pressure. The methodology of this work is based on experimental data acquisition of resonance characteristics of silicon cantilevers, combined with modification of analytical damping models to match the captured data. For this purpose, rectangular silicon cantilever beams with thicknesses of 5, 7, 8, 11, and 17 µ m and lengths and widths ranging from 70 to 1050 µ m and 80 to 230 µ m, respectively, have been fabricated and tested. Combining the three dominant damping mechanisms, i.e., the air damping, support loss, and thermoelastic damping, the variation in the measured Q-factors with the cantilever geometrical dimensions is predicted. Also to better describe the experimental data, modified models for air damping have been developed. These modified models can predict the optimum length and thickness of a resonant cantilever to achieve the maximum quality factor at the fundamental flexural resonance mode in air.
  • Item
    Nanojets – Formation, characterization and applications
    (Georgia Institute of Technology, 2008-12-21) Landman, Uzi ; Glezer, Ari ; Allen, Mark G. ; King, William ; Brand, Oliver ; Luedtke, William ; Gao, Jianping
  • Item
    Silicon-Based Resonant Microsensors
    (Georgia Institute of Technology, 2008-10-21) Brand, Oliver
    The presentation gives an introduction to resonant microsensors providing a frequency output signal. These sensors generally benefit from an excellent frequency resolution, which is ideally limited only by the length of the counting period and the short-term frequency stability of the microstructure's resonance frequency. Device-level and system-level approaches to generate a measurand-dependent frequency signal are discussed and concepts to improve Q-factor, short-term frequency stability and ultimately sensor resolution are highlighted. Furthermore, the presentation discusses frequency drift challenges and introduces methods for drift compensation. The above concepts and approaches are illustrated using two resonant microsensor examples: (i) a mass-sensitive microsensor platform for gas- and liquid-phase chemical sensing based on disktype silicon microstructures and (ii) a cantilever-based resonant magnetic microsensor with a resolution suitable for Earth field applications.
  • Item
    Temperature compensation method for resonant microsensors based on a controlled stiffness modulation
    (Georgia Institute of Technology, 2008-07-01) Seo, Jae Hyeong ; Demirci, Kemal Safak ; Byun, Albert ; Truax, Stuart ; Brand, Oliver
    A strategy to compensate for frequency drifts caused by temperature changes in resonant microstructures is presented. The proposed compensation method is based on a controlled stiffness modulation of the resonator by an additional feedback loop to extract the frequency changes caused by temperature changes. The feasibility of the suggested method is verified experimentally by compensating for temperature-induced frequency fluctuations of a micromachined resonator. The developed compensation scheme requires only one additional feedback loop and is applicable to any resonant microstructure featuring excitation and detection elements.